The present invention relates to a rapid-separation mounting arrangement for rollers in general, and more particularly to an arrangement of this type for use in calendering machines.
It is well known, particularly in the field of constructing calendering machines, to mount a plurality of treating, especially calendering, rollers for rotation in individual bearing blocks. The bearing blocks, in turn, are mounted on stationary guides fixed to a support or frame of the machine, for movement toward and away from one another with attendant movement of the rollers together and apart. Especially in a calendering machine, the guides extend substantially vertically so that the rollers are arranged one above the other, and so are the individual bearing blocks for the respective rollers. In this context, it has been proposed to employ a pressing arrangement mounted on the support and acting on the bearing blocks of the uppermost roller in the downward direction. Then, it is also known to associate a cylinder-and-piston unit with each of the bearing blocks of the lowermost roller, the cylinders of each of these units are being stationarily mounted on the support, while the pistons of these units are displaceable from a first position in which they lift the bearing blocks, under the influence of a pressurized hydraulic fluid medium in the cylinders, upwardly to positions of abutment against stationary abutment surfaces and downwardly following a reduction in the pressure of the pressurized fluid medium to a second position in which a gap exists between all of the above-mentioned rollers.
A calendering machine of this kind is disclosed, for instance, in the U.S. Pat. No. 2,861,504. This calendering machine includes two upright supports, each at the one side of the machine and each including two columns which are connected at their upper ends by a yoke and at their lower ends by a base. Guides are provided at the inner sides of the columns, and the bearing blocks of all of the rollers are slidingly guided on these guides. Moreover, abutments provided with the above-mentioned abutment surfaces are so connected to the guides as to be positively stationarily retained thereon. A mechanical pressing arrangement is supported on the upper yoke. The cylinder-and-piston unit is arranged in the base. When the piston of the unit presses the bearing blocks of the lowermost roller in the upward direction, the bearing blocks are positively clamped between the piston and the abutment surface so that there is obtained a defined operating position for the lowermost roller. However, the lowermost roller can be rapidly lowered out of this operating position.
As advantageous as this arrangement may be in all other respects, it exhibits the drawback that the forces required for the fixation of the operating position of the lowermost roller are transmitted to the upright columns of the supports. Hence, these columns have to be so dimensioned as to be able to withstand the loads resulting from the above-mentioned fixation forces in addition to the working loads which are required for the treatment of the web of material treated by the rollers. Inasmuch as the columns of the upright support have to be machined in order to make the guides, there result relatively large tolerances. The lateral play which is caused by such large tolerances results in oscillations in the first or operating positions of the lower rollers when, based on irregularities of the surfaces of the rollers or non-uniform thickness of the material to be handled, the various parts are excited into oscillation. Large tolerances also make it difficult, at least in part, to properly set or adjust the abutments. This known arrangement is not suited for the supports which are in use nowadays and which include only a single column.
There is further known a calendering machine disclosed in German Pat. No. 2,010,322 in which each of the upright supports includes only one column and thus only one guide for the rollers, which extends over the entire height of the respective column. In order to make it possible to guide the bearing block of the lowermost roller on both sides, a block with a second guide is stationarily mounted at the outer side of the base. The cylinder which is arranged in the base is provided with a lid that is rigidly connected thereto, the lid forming an abutment surface for a step provided on the piston.
In this construction, only the piston is positively guided. The bearing blocks of the lowermost rollers merely lie on the piston under the influence of the forces exerted thereon by the rollers and/or associated bearing blocks situated above the same. To this, there are to be added, even here, the manufacturing tolerances and deviations in parallelism of the two mutually independent guides. As a result of this freedom of movement of the lowermost roller, there are encountered operating disturbances in the form of intense vibrations and rattling phenomena. They cause deformation and finally damaging of the set of rollers and, as a result of this, also of the product to be treated such as, for instance, a paper web. The criticality of these disturbances increases with the length of the rollers and with the rate of their speed of rotation. As a result of this, any further technical development of machines of this type is considerably limited.
The above-discussed disadvantages become even more pronounced when a calendering machine with a heretofore non-displaceable lowermost roller is to be converted in a calendering machine capable of rapid separation of the individual rollers. More particularly, in a case like this, the one guide which is provided on the upright support must be manufactured in situ. This, of necessity, results in even greater tolerances than those obtained when the guide is manufactured in the manufacturing plant.